Geoff Duncan is one of several Republicans speaking at the DNC

Former Lt. Gov. Geoff Duncan speaks to reporters after testifying at Fulton County Courthouse in Atlanta on Monday, August 14, 2023. Fulton prosecutors are presenting their election interference case against former President Donald Trump and others to a grand jury. (Arvin Temkar / arvin.temkar@ajc.com)

Credit: Arvin Temkar/AJC

Credit: Arvin Temkar/AJC

Former Lt. Gov. Geoff Duncan speaks to reporters after testifying at Fulton County Courthouse in Atlanta on Monday, August 14, 2023. Fulton prosecutors are presenting their election interference case against former President Donald Trump and others to a grand jury. (Arvin Temkar / arvin.temkar@ajc.com)

Former Georgia Lt. Gov. Geoff Duncan is scheduled to speak at the Democratic National Convention on Wednesday, joining several other Republicans who will use the spotlight to urge conservatives to ditch Donald Trump in favor of Vice President Kamala Harris.

Duncan told The Atlanta Journal-Constitution that his “focus will be on the millions of Republicans watching at home that are sick and tired of making excuses for Trump everywhere they go.”

He’s one of several GOP figures who will speak during the nominating convention as Harris tries to drive a deeper wedge into Trump’s base. Former U.S. Rep. Adam Kinzinger and Republican commentator Anna Navarro are also expected to deliver remarks this week.

Duncan, a former professional baseball player, emerged as one of the nation’s most prominent Republican critics of Trump after he and other state leaders resisted the then-president’s attempts to overturn his narrow 2020 election defeat.

He’s since become a vocal critic of Trump and his allies. He refused to support Lt. Gov. Burt Jones, his successor, and Herschel Walker, the failed Trump-backed contender who challenged U.S. Sen. Raphael Warnock in 2022.

And, to the delight of Democrats, he endorsed President Joe Biden and then Harris. Infuriated Republicans, meanwhile, have tried to ban him from running for state and federal office on the GOP ticket and to treat him as a “trespasser” if he attends party events.